During the past year, we have been studying a variety of skin diseases for the presence or absence of circulating antigen-antibody complexes. Such complexes have been identified in sera of patients wth pemphigus, bullous pemphigoid, systemic lupus erythematosus and various forms of cutaneous vasculitis. The presence of these complexes appears to correlate with the presence of active disease in all of the above conditions. An attempt will be made during the next year to identify these complexes by other methods, to characterize them as immune complexes and to hopefully identify the responsible antigens. We will also continue to isolate and purify cutaneous antigens to compare them to the antigenic portion in the immune complexes mentioned above.